The present disclosure relates to amplifiers, and, more specifically, to power amplifiers using injection lock that is controlled by back-gate bias.
Current wireless technology trends towards increasing numbers of wireless standards and radio frequency (RF) bands to support wireless communications have led to the development of multi-standard, multi-band cellular systems. Such efforts have produced well-performing wideband receivers and frequency synthesizers. However, power amplifiers having the desired performance, output power, etc., across multiple frequency bands remains a challenge for such cellular systems.
Due to the fast-growing demand of wireless communication, a CMOS transceiver has been developed and has become available for the commercial market. However, there are still technical obstacles to achieve widespread application of millimeter-wave (mmWave) CMOS applications, especially in the design of Power Amplifier (PA). For example, the gain of a CMOS transistor at 60 GHz is typically small, so multiple-stage design is usually employed in order to obtain higher gain. In addition, power combining technology can be a solution to CMOS's low output power. However, the efficiency of a CMOS PA is usually low due to the poor RF performance of the transistor. Techniques, such as multi-stage design would further reduce the overall efficiency. An Injection Locking Power Amplifier (ILPA) can achieve high efficiency at 60 GHz in addition to providing high gain with a compact size. However, there are some major drawbacks of the ILPA.
Using current sources to tune the injection current and oscillator core current increases the headroom required and possibility of noise up-conversion. AC-coupling with resistor bias to de-coupled the dc biases in the oscillator core increases the loss, especially for mmWave applications.